Sandwich-type polyoxoanions based on A-β-GeW₉. Synthesis and characterization of [(A-β-GeW₉O₃₄)₂(MOH₂)₃CO₃]¹³⁻ (M = Y³⁺, Sm³⁺, and Yb³⁺) polyoxoanions

Abstract

The title complexes were synthesized at room temperature by the reaction of A-β-GeW₉ with MCl₃ (M = Y³⁺, Sm³⁺, and Yb³⁺) in 0.1 mol L⁻¹ sodium carbonate solution and characterized by elemental analysis, FT-IR, UV, ¹³C- and ¹⁸³W-NMR spectroscopies, and thermogravimetric analysis (TGA). Two-line ¹⁸³W-NMR spectrum with 2 : 1 intensity ratio confirms that [(A-β-GeW₉O₃₄)₂(MOH₂)₃CO₃]¹³⁻ contains an anion of D_3h symmetry. The difference of the two chemical shifts Δδ = 30.56 affirms the presence of A-β-GeW₉ . The chemical shift of the single-line ¹³C-NMR spectrum of [(A-β-GeW₉O₃₄)₂(MOH₂)₃CO₃]¹³⁻ and frequencies of stretching vibrations of all three complexes affirm the presence of coordinated carbonate. TGA shows that the complexes are thermally stable up to 430°C.

Keywords:

• Polyoxoanions
• Sandwich type
• A-β-GeW₉O₃₄
• Trivalent yttrium, samarium, and ytterbium ions
• ¹⁸³W-NMR spectroscopy